= Solution
\b[Unbroken extended supersymmetry obstructs the observed chiral matter structure.] In four dimensions, the matter <hypermultiplets> of $\mathcal N\ge2$ theories contain conjugate <gauge group representations>, so their <fermions> are vectorlike rather than the chiral <Weyl fermions> of the <Standard Model>. <Extended supersymmetry> also relates interactions more strongly, restricting independent <Yukawa couplings> and <superpotentials>. It can occur at higher energies and break to $\mathcal N=1$ or to no <supersymmetry>; the objection is to its unbroken realization in an ordinary low-energy chiral particle theory.
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